Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/36007—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation of urogenital or gastrointestinal organs, e.g. for incontinence control
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/36014—External stimulators, e.g. with patch electrodes
  • A61N1/3603—Control systems
  • A61N1/36034—Control systems specified by the stimulation parameters

Definitions

• Uterine atony causes more than 90 percent of cases of postpartum hemorrhage (5).
• Uterine atony is a loss of tone in the uterine musculature postpartum, resulting in the failure of uterine muscles to contract tonically and stop postpartum bleeding. This may be related to the inability of myometrial cells in some patients to act properly as pacemakers for tonic contractions after delivery (7), or may be related to changes in threshold or resting potentials brought on by the delivery process or by administration of medications (8).
• Some embodiments of the invention provide a method for treating insufficient uterine contractions after labor and delivery.
• the method may include generating electrical stimulating current signals at a frequency greater than or equal to about 5.0 Hertz and applying the electrical stimulating current signals to one of a cervix, a vagina, and a uterus to produce uterine tonic contractions.
• Some embodiments of the invention provide a system for treating insufficient uterine contractions in a patient after labor and delivery.
• the system may include a control module which performs at least one of preprogrammed stimulation tasks and user- defined stimulation tasks and a current source controlled by the control module to produce stimulating current at a frequency greater than about 5.0 Hertz.
• the system may also include one or more stimulation electrodes coupled to one of a uterus, a cervix, a vaginal wall, and an abdominal wall of the patient to provide the stimulating current to the patient in order for the patient to produce tonic uterine contractions.
• FIG. 1 illustrates different types of observable uterine contractile events.
• FIG. 2 is a graph illustrating a measured power of contracting uterine muscles at different action potential frequencies.
• FIG. 3 is a graph illustrating forces exerted by contracting uterine muscles over time when stimulating current is applied at different frequencies.
• FIG. 4 is a schematic of an in vitro setup for stimulating uterine tissue and measuring resulting contractile activity.
• FIG. 5 is a graph illustrating a contractile recording of rat uterine tissue when varying frequency in applied stimulation current.
• FIG. 6 is a graph illustrating a contractile recording of human uterine tissue, when varying frequency in applied stimulation current.
• FIG. 7 is a graph illustrating a contractile recording of human uterine tissue, when varying train duration in applied stimulation current.
• FIG. 8 is another graph illustrating contractile recordings of human uterine tissue, including a control trace and a test trace, when varying train duration in applied stimulation current.
• FIG. 9 is a another graph illustrating contractile recordings of human uterine tissue, when varying frequency outside conventional parameters in applied stimulation current, in accordance with one embodiment of the invention.
• FIG. 10 is a schematic view of a system according to one embodiment of the invention.
• FIG. 11 is a front cross-sectional view of a uterus.
• FIG. 12A is a side cross-sectional view of a uterus normally contracting postpartum.
• FIG. 12B is a side cross-sectional view of a ruptured uterus, which is not contracting post-partum due to uterine atony.
• FIG. 12C is a side cross-sectional view of a ruptured uterus being stimulated by the system of FIG. 10.
• the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. Where appropriate, the terms “stimulation” and “stimulated” are understood to refer to electrical stimulation and electrically stimulated, respectively.
• Some embodiments of the invention provide a system and method of treating uterine atony by administering electrical stimulation to the uterus.
• the electrical stimulation to the uterus can result in uterine muscle contractile activity, which can aid in decreasing and/or stopping uterine bleeding.
• some uterine contractile events can include spontaneous phasic contractions (spontaneous contractions which are short in duration and occur without outside stimulation), short stimulated phasic contractions (stimulated contractions which are shorter in duration and stop at or before the time stimulation is stopped), long stimulated phasic contractions (stimulated contractions which are longer in duration and stop immediately after the time stimulation is stopped), and tonic contractions (sustained contractions which persist long after stimulation is stopped).
• spontaneous phasic contractions spontaneous phasic contractions which are short in duration and occur without outside stimulation
• short stimulated phasic contractions stimulated contractions which are shorter in duration and stop at or before the time stimulation is stopped
• long stimulated phasic contractions stimulated contractions which are longer in duration and stop immediately after the time stimulation is stopped
• tonic contractions sustained contractions which persist long after stimulation is stopped.
• the human uterus exhibits spontaneous phasic contractions that produce associated electrical action potential frequencies in the range of 0.0 Hertz (Hz) to about
• the human uterus also exhibits spontaneous phasic contractions during menstrual cycles in non-pregnant women.
• electrical power output of uterine spontaneous phasic contractions is mostly concentrated at less than 1.0 Hz. Very little electrical power is observed in higher frequencies than the above-described range.
• FIG. 3 illustrates uterine muscle activity over time when a stimulation current is applied.
• uterine muscle action returns to baseline immediately after the current is switched off when using frequencies up to about 5 Hz.
• the maximal contractile activity begins to fall well before the current is turned off, which is indicative of stimulated phasic contractile activity.
• the stimulated phasic contractile activity shown in FIG. 3 can be considered short stimulated phasic contractions, as the stimulation duration is substantially small (e.g., less than about 3 minutes) and the stimulation frequency lies within the conventional uterine stimulation frequency range.
• short stimulated phasic contractions can be specified as having a minimal duration time of about 30 seconds and a maximum duration time of about 3 minutes.
• FIG. 4 illustrates an in vitro setup 10 for stimulating uterine tissue and measuring resulting contractile activity.
• the setup includes one or more strips 12 (i.e., strips of uterine muscle tissue) outfitted with a plurality of stimulation electrodes 14 at each end (i.e., through suturing) isolated in a bath 16 of Kreb's solution. Electrode lead wires 18 are Teflon-coated so as to act as insulation from the Krebs solution to prevent shorting of electrical current.
• the setup 10 also includes a source 20 for providing electrical stimulation with varying parameters.
• Tension force of the strips are recorded using a transducer (e.g., force gauge 21) and a computer obtains force data sensed by the transducer for analysis and display.
• a transducer e.g., force gauge 21
• a computer obtains force data sensed by the transducer for analysis and display.
• FIG. 5 illustrates resulting force data from a test strip 12 of rat uterine tissue, when varying the stimulation current frequency (at 1 Hz, 2 Hz, 3 Hz, and 5 Hz), with stimulation voltage and train duration fixed. Each frequency tested produced a visible contractile response, resulting in short stimulated phasic contractions.
• FIG. 6 illustrates resulting force data from a test strip 12 of human uterine tissue, with stimulation current frequency varied (at 1 Hz, 2 Hz, and 5 Hz), with stimulation voltage and train duration fixed. Each frequency tested produced a short stimulated phasic contraction.
• FIG. 5 illustrates resulting force data from a test strip 12 of rat uterine tissue, when varying the stimulation current frequency (at 1 Hz, 2 Hz, 3 Hz, and 5 Hz), with stimulation voltage and train duration fixed. Each frequency tested produced a short stimulated phasic contraction.
• FIGS. 7 illustrates resulting force data from a test strip 12 of human uterine tissue, with stimulation current train duration varied (at 1 second, 2 seconds, 3 seconds, 5 seconds, and 10 seconds), with stimulation voltage and frequency fixed. No noticeable response was seen from 1 -second and 2-second train durations. However, train durations of 3 seconds, 5 seconds, and 10 seconds produced short stimulated phasic contractions.
• the short stimulated phasic contractions shown in FIGS. 5-7 while useful for inducing or augmenting labor in women whose uterine function is insufficient for successful labor and delivery, are not useful for stopping blood loss during uterine atony and postpartum hemorrhage.
• FIG. 8 illustrates resulting force data from test and control strips 12 of human myometrial tissue that were obtained from a term patient (39 weeks gestation) who demonstrated insufficient contractile activity during labor. Electrical stimulation at about 10 volts in pulses of about 2 Hz were applied to the test strip 12. The pulses were run for a 5 minute duration (period 1), a 10 minute duration (period T), and a 20 minute duration (period 3).
• FIG. 8 shows spontaneous phasic contractile activity in the control strip 12 (top trace, no outside electrical stimulation provided), and spontaneous phasic contractile activity as well as stimulated phasic contractile activity in the test strip 12 (bottom trace, outside electrical stimulation provided by the source 20).
• the test strip 12 produced stimulated phasic contractile activity during period 1, period 2, and period 3 as a result of direct electrical stimulation of the test tissue.
• the duration of the stimulated phasic contractile activity was in direct proportion to the duration of the electrical stimulation current applied, and when the electrical stimulation current was turned off, the test strip force measurement returned fully to baseline, illustrating complete relaxation of the tissue.
• the stimulated phasic contractile activity shown in FIG. 8 can be considered long stimulated phasic contractions, as the stimulation duration is longer than about 3 minutes and the stimulation frequency lies within the conventional uterine stimulation frequency range.
• long stimulated phasic contractions may be substantially effective for reducing bleeding during postpartum hemorrhage and uterine atony, however, the amount of electrical energy required, and the length of time that the uterine tissue is exposed to such energy, may be too large to be of practical value in other embodiments.
• FIG. 9 illustrates resulting force data from two test strips 12 of human uterine tissue, with electrical stimulation frequencies varied (at 6 Hz, 10 Hz, 20 Hz) and with electrical stimulation current pulse train duration varied (at 60 seconds, 120 seconds, 300 seconds, 1200 seconds).
• Spikes shown in FIG. 9 indicate uterine muscle contractions.
• the spikes labeled "P” indicate initial preparatory contractions.
• the spikes labeled “S” indicate spontaneous uterine phasic contractions.
• the solid bars under the long spikes indicate the time periods during which electrical stimulation currents were applied to the uterine muscles. These time durations of electrical stimulation are indicated above the long spikes (in seconds) following the letter "E”.
• these tonic contractions i.e., forceful and sustained contractions
• tetanic contractions i.e., tonic contractions which remain maximally, or near-maximally, forceful
• Tonic contractile events are not possible to achieve using conventional electrical stimulation parameters (i.e., 0.0 Hz to about 5.0 Hz), which only seem capable of producing phasic contractions of the type observed during labor and delivery. Also, presently available drugs and systems, including oxytocin, are not capable of producing sustained, forceful contractions after treatment with them has completed. In some embodiments, only tonic contractions, achieved using frequencies at or above about 5.0 Hz, can be useful for contracting the uterus during critical bleeding in women with uterine atony and/or uterine rupture.
• FIG. 10 illustrates a system 22 according to one embodiment of the invention.
• the system 22 can stimulate uterine muscles into tonic contractions using frequencies greater than about 5.0 Hz.
• the system 22 can be used to stimulate muscles of the uterus in a way that does not affect other organs and can be accurately regulated and controlled, unlike oxytocin or other conventionally-used drugs.
• the system 22 can be used on a patient, such as a female post-partum, and can be controlled by a user, such as a physician or medical staff member.
• the system 22 can input innocuous electrical pulses into the patient's uterus with sufficient effect to incite postpartum tonic or tetanic contractions in order to help treat uterine atony and postpartum hemorrhage.
• the system 22 can include a control module 24, a current source 26, an isolation unit 28, a constant maximum current unit 30, a biphasic converter 32, a set of lead wires 34, and a set of electrodes 36.
• the control module 24 can contain computing capability, software, and memory.
• the controlling module 12 can be set using interface controls 33, such as dials, switches and/or auxiliary inputs, to perform preprogrammed stimulation tasks, including commanding the current source 26 to output stimulation current of selected frequency, amplitude, pulse width, and train duration automatically for selected periods of time.
• the control module 24 can also be operated manually by the user, in which the user can determine and set one or more output stimulation currents of desired frequencies, amplitudes, pulse widths, and train durations as needed spontaneously (i.e., in real time or in near-real time).
• control module 24 can be operated automatically or manually to produce a stimulation current which can cause tonic or tetanic contractions of the patient's uterine muscle and the user has the capability to adjust the stimulation current parameters (i.e., frequencies, amplitudes, pulse widths, and/or train durations) in real time or near-real time during observation of the patient's uterus.
• stimulation current parameters i.e., frequencies, amplitudes, pulse widths, and/or train durations
• control module 24 can automatically or manually operate multiple stimulation outputs of the current source 26 independently or in unison with varying or similar current frequencies, amplitudes, pulse widths, and train durations.
• control module 24 can provide stimulation currents directly to the uterus or through various organs, such as the cervix, vaginal wall and/or abdominal wall separately, simultaneously, or sequentially, or can provide stimulation currents to various parts of the uterus separately, simultaneously, or sequentially.
• pre-recorded uterine electrical traces obtained from normally-contracting patients and saved digitally, can be stored in the control module 24 to be used, in turn, as the electrical current trace patterns for commanding the current source 26 to output identical stimulation current to patients with abnormal uterine activity, such as patients with insufficient or absent contractile activity during postpartum hemorrhage.
• artificially generated current traces, saved digitally, with known frequencies, amplitudes, pulse widths, and train durations can be stored in the control module 24 to be used as the electrical current trace patterns for commanding the current source 26 to output identical stimulation current to patients with abnormal uterine activity during postpartum hemorrhage.
• control module 24 can automatically regulate and modify the electrical current output produced by the current source 26 based on input from electrical contractile activity of the patient's uterus, which can be transmitted to the control module 24 via pick-up wires, a signal conditioner, and/or after-conditioning wires (not shown).
• the control module 24 can regulate and modify the produced electrical current by changing the electrical stimulation pulse-width, current amplitude, pulse train duration, and/or the pulse frequency according to a pre-programmed algorithm.
• the control module 24 can include a display 37, such as a video display, a digital display, light-emitting diode (LED) display, etc., to display the stimulation output currents produced for the user to read or assess.
• the control module 24 can be coupled to the current source 26 by wires, direct electrical coupling, or another suitable coupling.
• the control module 24 can communicate with the current source 26 via a wireless connection, such as Bluetooth®.
• the current source 26 can generate the output stimulation current.
• the electrical stimulation current settings can be adjusted at the current source 26 by the user using interface controls 35, such as dials, switches or other settings.
• the electrical stimulation settings can be controlled by the control module 24 (e.g., as preprogrammed settings or by the user using the interface controls 33, as described above), and output to the current source 26.
• the current source 26 can output multiple electrical stimulation currents either directly to the uterus or indirectly to the uterus via the cervix, the vaginal wall and/or the abdominal wall separately, simultaneously, or sequentially, as commanded by the control module 24, or the current source 26 can output multiple electrical stimulation currents to various locations of the uterus separately, simultaneously, or sequentially.
• the current source 26 can be capable of generating an output current between about 0.01 milliamperes and about 40.00 milliamperes (with possible voltages between about 0.0001 volts and about 100 volts).
• Pulse widths of the current can be adjusted between about 0.1 millisecond and about 1000 milliseconds.
• Frequencies of the current can be adjusted from about 0.1 Hertz to about 30 Hz or greater.
• Pulse train durations can be adjusted from about 1 second to about 10,000 seconds.
• output currents can be sinusoidal so as to reduce tissue damage and maximize effect (10).
• the current source 26 can produce a maximal "jolt" of uterine electrical stimulation energy equivalent to between about 1 Joule and about 120 Joules of electrical energy in a short duration between about 1 millisecond and about 1000 milliseconds.
• the electrical stimulation current output from the current source 26 can be sensed, measured, or detected by either the current source 26 or the control module 24 and can be automatically shut off if current values are determined to be dangerous or outside prescribed, programmed, or set values.
• the isolation unit 28 can prevent ground loop currents from affecting the patient. In one embodiment, isolation is accomplished through optical isolation. In other embodiments, induction or other methods of isolation can be used by the isolation unit 28.
• the constant maximum current unit 30 can allow the user to regulate the amount of maximum current that the patient's uterus receives.
• the constant maximum current unit 30 can prevent tissue damage due to extreme current fluctuations as tissue resistance varies (11), and can be set (either in a discrete or continuous fashion) to or between values well below human threshold for human feeling (e.g., about 0.01 milliamperes) and values uncomfortable for humans (e.g., about 10 milliamperes).
• the constant maximum stimulation current can be set at a value which maximizes current input without damaging tissue and with minimal discomfort to the patient (e.g., about 4 milliamperes).
• the biphasic converter 32 can alternate the polarity of current pulses produced by the current source 26 after having moved through the isolation unit 28 and the constant maximum current unit 30 in order to further prevent adverse effects on the patient's tissues.
• the biphasic converter 32 can insure that the total energy delivered at the tissue site, as integrated over time, has a net value of zero. This can reduce the possibility of heating and subsequent damage to the patient's tissues (11, 12).
• the lead wires 34 can transmit the output current from the biphasic converter 32 to the electrodes 36.
• the lead wires 34 can be similar to those manufactured by Advantage Medical Cables.
• the system 22 can include between one and ten lead wires 34.
• different lead wires 34 can carry different types or strengths of currents that incite, induce, or augment a tonic contraction at different times in different parts of the uterus, as preprogrammed or set by the user (e.g., to stimulate various parts of the patient's uterus separately, simultaneously, and/or sequentially).
• FIG. 11 illustrates a patient's uterus 38, ovaries 40, fallopian tubes 42, a uterine body (or intrauterine cavity) 44, a cervix 46, a vagina 48, a fundus 50 (i.e., top portion) of the uterus, and a distal portion 52 of the uterus.
• the electrodes 36 can be attached to or near the uterus 38 in a specific orientation and at specific locations that will have the best effect upon uterine contractility for the patient, as determined by the user.
• the electrodes 36 can be placed upon the vaginal wall 48 and/or the cervix 46.
• the electrodes 36 can be placed at locations across the fundal 50 and distal portions 52 of the uterus 38.
• the electrodes 36 can be mounted externally to the patient's abdominal surface.
• the electrodes 36 can be attached to the patient's abdominal surface and/or uterus 38 using biocompatible glue or tissue adhesive, or by suction or other self-affixing electrodes.
• the electrodes 36 can be standard silver chloride (AG2C1) electrodes, EEG electrodes, suction electrodes, or needle electrodes.
• the system 22 can include between one and ten electrodes 36 (e.g., equal to the number of lead wires 34). Different electrodes 36 can be positioned at various locations in or around the patient's uterus 38, where some or each of the electrodes 36 causes tonic and/or phasic effects according to the electrical stimulus applied through them.
• one or several electrodes 36 can act as a local pacemaker for eliciting contractions, while one or several other electrodes 36 can cover one or many different portions of the uterus 38 for eliciting global tonic or tetanic contractions.
• the electrodes 36 can consist of platinum- iridium metals, so as to reduce the possibility of tissue lesions (12).
• FIGS. 12A-12C illustrate a patient's uterus 38 in three different conditions.
• FIG. 12A shows a naturally contracting uterus 38 post-partum. Forceful and spontaneous tonic contractions can prevent blood loss.
• FIG. 12B shows a uterus 38 which is not contracting postpartum due to uterine atony. The lack of tonic contractile activity allows the uterus to bleed out, threatening the life of the patient.
• FIG. 12C shows the uterus 38 with atony and uterine rupture treated effectively (i.e., forcefully contracted) using electrical tonic stimulation. As shown in FIG.
• the uterus 38 has been outfitted with electrodes 36 (trans-vaginally) so that the system 22 can output stimulated current (i.e., through the lead wires 34) for tonic activity using electrical frequencies greater than or equal to about 5 Hz.
• the artificially-stimulated tonic contractions can help reduce, stop and/or manage the blood loss.
• the stimulated current can be output to the patient for a duration greater than about 10 seconds.
• the pulse train durations can be up to about 30 minutes long.
• system 22 can be used in conjunction with other devices, methods, systems, and treatments for postpartum hemorrhage, uterine atony, and bleeding or coagulation problems, including but not limited to oxytocin, prostaglandins, misoprostol, prepidil, ergot alkyloids, tamponades, balloon tamponades, sponges, clamps, manual uterine massage and manipulation, sutures, bio-compatible adhesives, cauterization, and/or pharmaceutical coagulants.
• other devices, methods, systems, and treatments for postpartum hemorrhage, uterine atony, and bleeding or coagulation problems including but not limited to oxytocin, prostaglandins, misoprostol, prepidil, ergot alkyloids, tamponades, balloon tamponades, sponges, clamps, manual uterine massage and manipulation, sutures, bio-compatible adhesives, cauterization, and/or pharmaceutical coagulants.

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